|MadSci Network: Chemistry|
For those who are neither medicos nor organic chemistry minors, here is a brief run-down of what is going on. Animal hair is largely made of protein, and the sort of giant protein molecule that is involved has quite a lot of sections of the sulfur-containing amino-acid cystine. The sort of micro- organisms that live in wet, low oxygen environments like the U-bend traps in plumbing, get the energy to keep them alive and multiplying by eating their way through any sort of waste organic material. They turn it mainly into methane and carbon dioxide. Methane is not much of a problem: it is almost odourless, and only relatively small quantities are involved. The real problem is that any sulfur that was present in the original organic material finishes up as hydrogen sulfide and/or dimethyl sulfide -- rotten egg gas -- and these gases are both very toxic and very smelly. A small amount goes a very long way! So you have tried two remedies. It is not surprising that neither will work. Antibacterials will kill most or perhaps even all of the current colonies of microorganisms. But that will just leave a vacant lot rich in nutrients in the microbial world -- it will be rapidly taken over by new tenants. Caustic soda works in two ways. It will also kill the current colonies of microbiota. And it is an alkali that will react with hydrogen sulfide (not dimethyl sulfide!) to form water-soluble and non-smelly sodium sulfide. But only for as long as that water stays alkaline. As soon as neutral or acidic water gets back into the trap, new colonies of mocroorganisms will return, and so will the smell. The real question that you ask is "any suggestions". As a medico you will appreciate that this must be tackled in two parts: prevention amd cure. I think I can help with the prevention bit. If there is no convenient alternative to your shower for rottweiler bathing, by far the most effective thing you can do is to fix a much finer filter over your plug hole, so that the hairs are caught in a position where they can conveniently be manually removed and disposed of. If no suitable commercial product is readily available, I would suggest stretching some nylon or fibreglass shadecloth or insect screen over a frame and gluing or screwing that over your plughole. The cure is more difficult. Antibacterials and caustic soda are two of the three obvious approaches. I can suggest a third -- an oxidizing agent like peroxide, which will permanently convert rotten egg gas to harmless sulfates. But none will work very well because of the problems I outlined previously. What you need is a "slow release" solution. A slow release solution that kills the microbiota does not solve the problem, but merely holds it at bay: the existing load of hair will not rot, but just stay there for future use. The best solution, though hardest to achieve, would be to somehow produce a high oxygen environment in your shower U-bend, so as to encourage colonies of aerobic microbes to do the job. They use oxygen with the organic matter to produce carbon dioxide; no methane is produced, and sulfur is converted to sulfates rather than rotten egg gas. Physically removing the current crop of rotting hair from the U-bend may prove easiest after all, either by getting in at it, or by devising some way to comprehensively push it further down the waste water system.
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